Little is known about the specific genes involved in the processes of taste transduction and taste cell differentiation. Genes coding for components of taste transduction pathways will be specifically expressed in mature taste buds, while genes involved in taste cell differentiation are likely to be differentially regulated during taste bud development. The focus of this proposal is to isolate taste cell-specific genes from mature taste cells as well as taste cells at different developmental stages. The long range goal is to use these novel genes to examine the processes of taste transduction and taste cell differentiation. Specific Aim 1. Isolate taste cell-specific genes from adult taste buds. Although the basic mechanisms of taste transduction have been characterized, few specific proteins involved in these processes have been isolated. Some of these proteins (e.g., taste receptors), are undoubtedly unique to taste buds and may not have sufficient homology to other proteins to be isolated using the PCR or low stringency cDNA library screening. A PCR-based subtractive hybridization technique will be applied to the taste system to identify and isolate genes coding for proteins that are specifically expressed in mature taste buds. Such genes are likely to play a role in taste transduction. Specific Aim 2. Isolate and identify genes that are differentially expressed during taste bud development. Genes that regulate taste cell differentiation are themselves likely to be developmentally regulated. Once PCR subtractive hybridization has been optimized for use in the taste system (Specific Aim 1), the technique will be applied to isolating genes that are differentially regulated during taste bud development. The genes will be screened to determine their temporal regulation during taste bud development and regeneration. Even before a specific function is assigned, they can provide useful markers for studying taste bud development and taste cell differentiation.